Assigning Processor Affinity

Updated: August 22, 2005

Applies To: Windows Server 2003, Windows Server 2003 with SP1

To efficiently use CPU caches on multiprocessor servers, you can configure application pools to establish affinity between worker processes and the processors, a feature known as processor affinity. Processor affinity forces worker processes to run on specific CPUs, and applies to all worker processes serving a particular application pool. You can also use processor affinity with Web gardens that run on multiprocessor computers where specific application pools are dedicated to specific clusters of CPUs.

Processor affinity typically yields the greatest performance benefits when you configure affinity on a computer that has eight or more processors. You can set processor affinity from the command line by using the set command with Adsutil.vbs. To set processor affinity, configure the SMPAffinitized and SMPProcessorAffinityMask metabase properties.

Table 3.8 shows which processors, on a computer with eight processors, are made available to worker processes that serve an application pool when various processor affinity masks are assigned.